Antônio Carlos de Oliveira Ruellas

Dentofacial morphology of mouth breathing children

The relationship between dentofacial morphology and respiration has been debated and investigated from various approaches. The aim of this study was to verify the skeletal and dental relationship of mouth and nose breathing children. Thirty-five children, 7 to 10 years of age, were submitted to orthodontic and otorhinolaryngologic evaluations and were separated into 2 groups: 15 nose breathers and 20 mouth breathers. Each subject underwent a cephalometric radiograph analysis. Statistical analysis (Mann-Whitney U test) indicated that changed mode of breathing was associated with 1) maxillo-mandibular retrusion in relation to the cranial base in the mouth breathers; 2) the SNGoGn and NSGn angles were greater in the mouth breathing group; 3) incisor inclination in both jaws and the interincisal angle were not different between groups. There was no statistically significant difference in the maxillary and mandibular molar heights between the nose breathers and mouth breathers.

Severe root resorption in orthodontic patients treated with the edgewise method: Prevalence and predictive factors

INTRODUCTION Our aims in this study were to assess the prevalence of severe root resorption and identify possible associations in orthodontic patients treated with the edgewise method. METHODS The sample included 1049 patients who had periapical radiographs taken for all incisors before and after treatment. The radiographs were examined by 2 orthodontists using an x-ray viewer with standard light intensity. These variables were collected: root shape, overbite, initial resorption, and hypodontia. The patients were classified according to sex, Angle classification, ethnicity, age, duration of treatment, type of dentition (mixed or permanent), and treatment with or without extraction of 4 premolars. Resorption was considered severe when it affected more than a third of the length of the root. Statistical analysis included the chi-square test and both simple and multiple logistic regression (P < or =0.05). RESULTS Severe root resorption was observed in 14.5% of the sample. Patients treated with exodontia of the first premolars (odds ratio [95% CI] = 6.38 [4.2-9.7]), those who had triangle-shaped roots at the beginning of treatment (odds ratio [95% CI] = 4.67 [3.1-6.9]), and those with initial root resorption (odds ratio [95% CI] = 4.52 [2.7-7.6]) had a greater chance of developing severe root resorption during orthodontic treatment. CONCLUSIONS A high prevalence of severe root resorption was observed in Brazilian patients treated with the edgewise method. The main factors directly involved in severe resorption were extraction of first premolars, triangle-shaped roots, and root resorption before treatment.

Effects of orthognathic surgery on oropharyngeal airway: a meta-analysis.

Oropharyngeal changes caused by orthognathic surgery have been a concern because the sleep quality of patients may be enhanced or worsened by these changes. The purpose of this meta-analysis was to identify, review and compare scientific literature about changes in airway in adult patients undergoing orthognathic surgery to correct anteroposterior osseous discrepancies. An electronic search of four databases was carried out up to July 2010, with supplemental hand searching of the references of the retrieved articles. Quality assessment of the included articles was carried out. Data were extracted and a meta-analysis was performed. Heterogeneity was assessed amongst the studies and results were presented in forest plots. 49 studies met the inclusion criteria. Only studies with moderate or high methodological soundness were included in the review. Moderate evidence was found to support a significant decrease in the oropharyngeal airway in mandibular setback surgery, a milder decrease in bimaxillary surgery to correct Class III and an increase in maxillomandibular advancement surgery. Evidence is lacking on airway volume changes after orthognathic surgery.

Longitudinal study of anteroposterior and vertical maxillary changes in skeletal class II patients treated with Kloehn cervical headgear.

This is a study to evaluate the posttreatment and long-term anteroposterior and vertical maxillary changes in skeletal Class II Division 1 patients (ANB > or = 5 degrees) who had received Kloehn cervical headgear treatment. The sample consisted of 120 lateral cephalograms obtained at pretreatment (T1), posttreatment (T2), and postretention (T3) phases of 40 patients (18 males and 22 females). The patients were of an average age of 10% years in phase T1, 13% years in phase T2, and 23% years in phase T3. They were treated with cervical traction and an expanded inner bow (4-8 mm) and a long outer bow bent upwards off the horizontal 10-20 degrees in relation to the inner bow. After correction of the molar relationship on both sides, a conventional edgewise fixed appliance was used to complement the correction of the malocclusion. The onset of treatment was either at the late mixed dentition or at the beginning of the permanent dentition. The force applied for the 40 patients averaged 450 g and the recommended use of the appliance was 12-14 hours per day with monthly adjustments. F-Snedecor test was applied to the entire sample and multiple comparisons between phases were tested by the Bonferroni method. Results revealed that treatment had reduced maxillary protrusion, inclined the palatal plane with an increase in the SN-PP angle with reduction at long-term. In conclusion, Kloehn cervical headgear with elevated external bow and expanded inner bow was efficient in correcting the skeletal Class II in late mixed-early permanent dentition. Skeletal Class II correction with Kloehn cervical headgear was found to be very stable long term.

Evaluation of pharyngeal airway space amongst different skeletal patterns

The aim of the present study was to evaluate the dimensions of the pharyngeal airway space (PAS) in awake, upright children with different anteroposterior skeletal patterns using cone beam computed tomography (CBCT). The volume, area, minimum axial area and seven linear measurements of PAS were obtained from the CBCT images of 50 children (mean age 9.16 years). The patients were divided in two groups according to the ANB angle (group I 2° ≤ ANB ≤ 5°; group II ANB > 5°). Means and standard deviations of each variable were compared and correlated using independent t-test and Pearsons correlation test. There were statistically significant differences in the following parameters: angle formed by the intersection between NA and NB lines (p<0.001), angle formed by the intersection between SN and NB lines (p<0.05), Minimal pharyngeal airway space between the uvula and the posterior pharyngeal wall (p<0.05), airway volume (p<0.01), airway area (p<0.01) and minimum axial area (p<0.05). The anteroposterior cephalometric variable SNB had positive correlation with the variables PAS-UP (p<0.01), Minimal pharyngeal airway space between the uvula tip and the posterior pharyngeal wall (p<0.05), Pharyngeal airway space on mandibular line (p<0.05), Minimal pharyngeal airway space between the back of the tongue and the posterior pharyngeal wall (p<0.05), volume airway (p<0.05), airway area (p<0.05) and minimum axial area (p<0.05). The vertical cephalometric variables angle formed by the intersection between SN and GoGn lines (p<0.05) and angle formed by the intersection between FH and mandible plane (p<0.05) showed negative correlation with PAS-UT. These results showed that PAS was statistically larger in group I than group II, indicating that the dimensions of the PAS are affected by different anteroposterior skeletal patterns.

Shear bond strength of brackets bonded with hydrophilic and hydrophobic bond systems under contamination

OBJECTIVE To compare, in vitro, the shear bond strength (SBS) of two bond systems: Transbond XT/XT primer (TXT/XT) and Transbond Plus Color Change/Transbond Self Etching Primer (TPCC/TSEP). MATERIALS AND METHODS Each system was examined under four enamel surface conditions (dry, water, saliva, and blood), and 160 bovine teeth were divided into eight groups of 20 according to enamel surface condition. Group 1 used TPCC/TSEP and Group 2 used TXT/XT under dry conditions; Group 3 used TPCC/TSEP and Group 4 used TXT/XT with water; Group 5 used TPCC/TSEP and Group 6 used TXT/XT under saliva; and Group 7 used TPCC/TSEP and Group 8 used TXT/XT with blood. Brackets were bonded, and the samples were thermocycled 500 times between 5 degrees C and 55 degrees C; they were then submitted to a shear bond test with a universal testing machine with a 50 kgf load cell at 5 mm/min. RESULTS Although water and saliva affected TXT/XT more than they affected TPCC/TSEP, there were no significant differences among the groups (Groups 3 and 4: P = .940; Groups 3 and 5 and Groups 4 and 6: P = 1.000; Groups 3 and 6: P = .988; Groups 4 and 5: P = .690; and Groups 5 and 6: P = .861). CONCLUSIONS The presence of blood resulted in the lowest SBS from both bond systems, but especially from TXT/XT. TPCC/TSEP resulted in a higher SBS than TXT/XT under all conditions except the dry enamel surface.

Is the airway volume being correctly analyzed

INTRODUCTION The aim of the study was to determine the most accurate threshold value for airway volume quantification based on specific experimental conditions. METHODS Ten scans from the airway prototype were obtained by using cone-beam computed tomography. The volume from each scan was measured with 8 values (25, 50, 70, 71, 72, 73, 74, and 75) of the threshold tool from the Dolphin software (Dolphin Imaging and Management Solutions, Chatsworth, Calif). The gold standard method used was the actual volume of the airway prototype, which was compared with the different threshold values. An intraclass correlation coefficient test was applied to evaluate the intraexaminer calibration and verify differences among the airway volumes measured in all cone-beam computed tomography scans. Analysis of variance with the Tukey post-hoc test was used to compare differences among the measurements with different threshold values with the gold standard. RESULTS The intraexaminer reliability was confirmed by the intraclass correlation coefficient, which was ≥0.99. The intraclass correlation coefficient used to verify the differences among the airway volume measurements in all cone-beam computed tomography scans was ≥0.98, showing that they were comparable. Analysis of variance and the Tukey post-hoc test showed that the volumes measured with the threshold values of the 25 and 50 filters had statistically significant differences from the gold standard. However, volumes measured with the threshold values of the 70, 71, 72, 73, 74, and 75 showed no statistically significant differences from the gold standard and among them. CONCLUSIONS In our study for the cone-beam machine and the acquisition parameters used, the threshold value of the 73 used in Dolphin 3D software was the most accurate to measure airway volume, but the threshold values of the 70, 71, 72, 74, and 75 had no statistically significant differences compared with the gold standard, showing they are also reliable.

Shear bond strength of orthodontic brackets to enamel under different surface treatment conditions.

The purpose of the present study was to evaluate the shear bond strength to enamel and the adhesive remnant index (ARI) of both metallic and polycarbonate brackets bonded under different conditions. Ninety bovine permanent mandibular incisors were embedded in acrylic resin using PVC rings as molds and assigned to 6 groups (n=15). In Groups 1 (control) and 3, metallic and polycarbonate orthodontic brackets were, respectively, bonded to the enamel surfaces using Transbond XT composite according to the manufacturers recommendations. In Groups 2 and 4, both types of brackets were bonded to enamel with Transbond XT composite, but XT primer was replaced by the OrthoPrimer agent. In Groups 5 and 6, the polycarbonate bracket bases were sandblasted with 50-μm aluminum-oxide particle stream and bonded to the enamel surfaces prepared under the same conditions described in Groups 3 and 4, respectively. After bonding, the specimens were stored in distilled water at 37°C for 24 hours and then submitted to shear bond strength test at a crosshead speed of 0.5 mm/min. The results (MPa) showed no statistically significant difference between Groups 4 and 6 (p>0.05). Likewise, no statistically significant differences (p>0.05) were found among Groups 1, 2, and 5, although their results were significantly lower than those of Groups 4 and 6 (p<0.05). Group 3 had statistically significant lower bond strength than Groups 2, 4, and 6, but no statistically significant differences were found on comparison to Groups 1 and 5. A larger number of fractures at the bracket/composite interface were evidenced by the ARI scores. OrthoPrimer bonding agent yielded higher bond strength in the groups using either conventional or sandblasted polycarbonate brackets, which was not observed in the groups using metallic brackets.

Reliability of upper airway linear, area, and volumetric measurements in cone-beam computed tomography.

INTRODUCTION Our objective was to assess the intraexaminer and interexaminer reliabilities of upper airway linear, area, and volumetric measurements in cone-beam computed tomography. METHODS Cone-beam computed tomography scans of 12 subjects were randomly selected from a pool of 132 orthodontic patients. An undergraduate student, an orthodontist, and a dental radiologist independently made linear, area, and volumetric measurements. Linear anteroposterior and transversal measurements, cross-sectional area, sagittal area, minimum axial area, and volume measurements were made. The intraclass correlation coefficient (ICC) was used to assess intraexaminer and interexaminer reliabilities, and measurement errors were assessed. Agreement was further assessed with the Bland-Altman method and 95% limits of agreement. RESULTS Overall, the ICC values indicated good reliability for the measurements assessed. The ICC values were greater than 0.9 (excellent) for 93% of intraexaminer and 73% of interexaminer assessments. Transversal width measurements and cross-sectional area at the level of the vallecula, however, had only moderate reliability (minimum ICC, 0.63), large 95% limits of agreement, and the greatest mean measurement errors (as high as 16% and 13% of the mean measurements, respectively). Linear anteroposterior measurements; cross-sectional areas at the levels of the palatal plane, soft palate, and tongue; and sagittal area and volume were reliable measurements, with a minimum ICC of 0.93 and more restricted limits of agreement. CONCLUSIONS Based on these results, airway assessments by examiners with different backgrounds might have reliable anteroposterior linear measurements; cross-sectional areas at the levels of the palatal plane, soft palate, and tongue; and sagittal area and volume. The unreliable measurements were linear width, cross-sectional area at the level of the vallecula, and minimum axial area.

Mandibular changes in skeletal class II patients treated with Kloehn cervical headgear

This study evaluated the posttreatment and long-term anteroposterior and vertical mandibular changes in skeletal Class II Division 1 patients (ANB angle >or= 5 degrees ) treated with Kloehn cervical headgear. The sample consisted of 40 patients (18 males, 22 females, average age 10.5 years at pretreatment [T1], 13.5 years at posttreatment [T2], and 23.5 years at postretention [T3]) treated with cervical traction with an expanded inner bow (4-8 mm) and a long outer bow bent upwards off the horizontal 10 degrees to 20 degrees in relation to the inner bow. The force applied averaged 450 g, and the recommended use of the appliance was 12 to 14 hours per day, with monthly adjustments. The Student t test was used for comparison between stages. Results showed that during treatment no significant change was found in the mandibular plane angle, but a significant decrease was detected at T3. Kloehn cervical headgear was efficient in the skeletal Class II correction. The superimposition of tracings suggests that much of the treatment effect occurs when the mandible is displaced forward. Skeletal Class II correction with Kloehn cervical headgear was found to be stable over the long term.